Methods for sensing or stimulating activity of tissue

ABSTRACT

An intravascular device for placement within an animal vessel, the intravascular device being adapted to at least one of sense and stimulate activity of neural tissue located outside the vessel proximate the intravascular device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/348,863 filed Mar. 31, 2014, which is a U.S. national applicationfiled under 35 U.S.C. 371 of International Application No.PCT/AU2012/001203 filed Oct. 3, 2012, which claims benefit of priorityto U.S. Provisional Application No. 61/542,822 filed Oct. 4, 2011, thecontents of which are incorporated by reference herein in theirentireties.

TECHNICAL FIELD

In a particular aspect, the present invention may relate tointravascularly sensing or stimulating electrical activity of neuraltissue.

BACKGROUND ART

Any discussion of documents, devices, acts or knowledge in thisspecification is included to explain the context of the invention. Itshould not be taken as an admission that any of the material forms apart of the prior art base or the common general knowledge in therelevant art in Australia or elsewhere on or before the priority date ofthe disclosure and broad consistory statements herein.

The ability to sense or stimulate nervous tissue in an animal confersmany therapeutic, analytic, and diagnostic advantages or opportunities,some of which may become apparent on further reading of thisspecification.

Without being an admission of common general knowledge, currenttechniques for measuring electrical activity of the brain involve theuse of extra-cranial electrodes placed on the scalp, or intra-cranialelectrodes surgically implanted on the outer cortical surfaces of thebrain, or in the epidural or subdural spaces.

Unfortunately there are significant disadvantages associated with thesecurrent methods. For example, there may be a lack of clarity orpredisposition to disturbances such as noise or movement when usingextra cranial electrodes applied externally on the scalp.

Further, when using intra cranial electrodes, there is a requirement forinvasive surgery to be performed. This carries considerable risk ofcomplications such as infections or bleeding, and only provides accessfor electrode placement on the outer surfaces of the brain, at leastwithout cutting into and damaging the brain.

Relocation of an implanted electrode may be required where furtherinvestigation of a different region of the brain is desired, or wherethe signal from the electrode has deteriorated due to scar formationabout the site of implantation. However, there are also difficultiesassociated with relocation of electrodes due to the requirement forfurther invasive surgery and possible entrapment of the electrode inscar tissue.

Current intra cranial electrodes can also require a direct electricalconnection to computer equipment which is located external to thepatient's body.

Thus, it may be advantageous to provide a new method or means forsensing or stimulating neuronal cells or neural tissue which reduces,limits, overcomes, or ameliorates some of the problems, drawbacks, ordisadvantages associated with prior art devices or methods, or providesan effective alternative to such devices or methods.

DISCLOSURE OF THE INVENTION

In one aspect the invention may provide an intravascular device forplacement within an animal vessel, the intravascular device beingadapted to sense or stimulate activity of neural tissue located outsidethe vessel proximate the intravascular device.

The neural tissue may comprise neuronal cells. The device may be adaptedto sense or stimulate activity of one or more neuronal cells.

The intravascular device may comprise a sensor adapted to sense activityof neural tissue located outside the vessel proximate the intravasculardevice.

The intravascular device may comprise a stimulator adapted to stimulateactivity of neural tissue located outside the vessel proximate thestimulator.

Thus, the intravascular device may comprise at least one of a sensor anda stimulator for respectively sensing or stimulating activity or neuraltissue located outside the vessel proximate the intravascular device.

The intravascular device, or sensor or stimulator thereof, may comprisean electrode. The electrode may be adapted to engage the wall of thevessel. The electrode may protrude slightly from the outer surface ofthe intravascular device.

The electrode may comprise an inert substance. The inert substance maycomprise platinum or nitinol. The use of an inert substance may allowdeposition of the electrode within the vessel for several years, or theremainder of the animal's life.

There may be multiple electrodes. For instance, there may be a pluralityof electrodes arranged in 2 times.4 array.

The intravascular device, or the sensor thereof, may be adapted to senselocal field potentials from proximate neural tissue. Additionally, oralternatively, the intravascular device, or the sensor thereof, may beadapted to sense electrical activity of a single neuron of the proximateneural tissue. Thus the intravascular device may be adapted to sense anaction potential of a neuronal cell.

The intravascular device, or the stimulator thereof, may be adapted tostimulate a local field potential in proximate neural tissue.Additionally, or alternatively, the intravascular device, or stimulatorthereof, may be adapted to stimulate electrical activity of a singleneuron of the proximate neural tissue. Thus the intravascular device maybe adapted to stimulate an action potential in a neuronal cell.

The electrode may be disposed on a mounting member. The mounting membermay comprise the electrode. The mounting member may be adapted toconduct electrical signals. Thus, the mounting member may comprise anelectrically conductive member.

The intravascular device may comprise the mounting member. The mountingmember may comprise silicone.

Suitably, the mounting member may be encased in a stable substance. Thestable substance may encase the mounting member and electrode. Thestable substance may comprise silicone.

The mounting member may comprise a board. The board may be encased insilicone. The board may comprise a printed circuit board.

The mounting member may comprise a flexible flap. The flexible flap maycomprise silicone.

The mounting member may comprise a wire, or a wire may be disposed onthe mounting member. There may be a plurality of wires.

The intravascular device may comprise a microchip. The microchip may beelectrically connected to the electrode. The wire may extend between theelectrode and the microchip.

The microchip may comprise a microprocessor.

The microchip may comprise a channel amplifier.

The microchip may comprise a digital signal converter.

The microchip may comprise an RF transmitter/receiver.

The wire may extend from the electrode to an external device locatedoutside of the body of the animal. There may be multiple wires extendingfrom multiple electrodes. The wires may congregate to form a bundlewhich passes out of the body of the animal.

In another aspect, the invention may provide a retainer for retainingthe intravascular device at a position within the vessel. Theintravascular device may be disposed on the retainer

The retainer may be expandable. The retainer may comprise a stent. Thestent may comprise a mesh framework. The stent may be expandable to takethe shape of the surrounding vessel.

The stent may comprise a biodegradable or bioabsorbable substance. Thestent may be gradually broken down inside the body.

Alternatively, the stent may comprise an inert substance such as nitinolor platinum. Thus the stent may remain functional in the body forseveral years, or even the lifetime of the animal.

The retainer may comprise a probe. The probe may comprise an elongateflexible micro-tube.

The stent may be adapted to expand when ejected out of an end of theprobe. The stent may be adapted to contract when retracted into theprobe. Thus the stent may be adapted to be deployed, retrieved, andre-deployed. The redeployment may take place at a different regionwithin the vessel to that of the earlier deployment.

In another form, the intravascular device may be mounted on the probe.The stent may be absent in such an embodiment. The probe may be adaptedto conduct electrical signals to or from the intravascular device. Theprobe may comprise a guide wire or cable. The electrode wires mayelectrically connect with the guide wire or cable.

The retainer may comprise an adhesive substance adapted to causeadhesion of the intravascular device to the inside of the vessel wall.The adhesive substance may be present on an outer surface of theintravascular device.

In another aspect, the invention may provide a system for sensing orstimulating activity of neural tissue comprising an intravascular devicefor placement within an animal vessel, the intravascular device beingadapted to sense or stimulate activity of neural tissue located outsidethe vessel proximate the intravascular device.

The system may further comprise a guide member for guiding theintravascular device to a region within the vessel proximate the neuraltissue to be sensed or stimulated.

The guide member may be adapted for passing into and through the animalvessel. The guide member may be adapted for passage of the intravasculardevice therethrough.

The guide member may comprise a catheter. Thus, the intravascular devicemay be passed through the catheter to a region within the vesselproximate the neural tissue to be sensed or stimulated.

The catheter may be flexible. The external diameter of the catheter maybe less than 3 millimetres. The internal diameter of the catheter may begreater than 0.5 mm.

The system may comprise a retainer or retaining member for retaining theintravascular device at a region within the vessel proximate the neuraltissue to be sensed or stimulated. The retaining member may be adaptedfor passage through the guide member.

The system may comprise an electronic system.

The electronic system may comprise an electrode of the intravasculardevice, and an electrically conductive member connected with theelectrode.

The electronic system may comprise a processor. The processor may belocated within or without the body of the animal. For example, in oneembodiment the processor is an internal processor in the form of amicroprocessor which is mounted on the intravascular device, whereas inanother form the electrodes are electrically connected to an externalprocessor such as a computer. In yet another form, the processor may bean internal processor in the form of a microprocessor which is mountedon a unit located in the body separately to the intravascular device.The processor may comprise a channel amplifier.

The processor may comprise a digital signal converter.

The processor may comprise an RF transmitter/receiver.

The processor may comprise at least one of an internal processordisposed on the intravascular device, and an external processor which ispresent outside the body.

A wireless form of the intravascular device may comprise the internalprocessor. The internal processor may comprise a channel amplifier,digital signal converter and RF transmitter/receiver.

A non-wireless version of the intravascular device may comprise theexternal processor. The external processor may comprise the channelamplifier and the digital signal converter. The RF transmitter/receivermay be absent in the non-wireless version. This omission may be made dueto power being directly received from an external power source, orsignals being directly transmitted through a solid medium such as awire. Thus, the system may comprise a unit. The unit may be locatedseparately to the intravascular device. The unit may be locatedinternally or in the body. In a particular form, the unit may be locatedsubcutaneously in the pectoral region. There may be more than oneinternal unit. Additionally or alternatively, the unit may be locatedexternally. For instance, the unit may be mounted on the patient's head.Thus, the system may comprise at least one of an internal unit and anexternal unit. Where there is an internal unit, an external unit may bepaired for wireless coupling therewith.

The external unit may be adapted to communicate wirelessly with theinternal unit. The external unit may be adapted for placement about aregion of the body adjacent the internal unit.

The unit may be connected by an elongate electrically conducting member,such as a wire, to the intravascular device. The electrically conductingmember may run substantially through the vasculature between the unitand the intravascular device.

It may be that the internal unit, or one of the internal units, isconnected by wire to the intravascular device, whereas the externalunit, or one of the external units, is electrically connected to anexternal device. The external device may comprise at least one of acomputer, stimulation box, and prosthetic limb.

The unit may comprise a retaining mechanism for retaining the unit inthe desired position. The retaining mechanism may comprise suture holes.The unit may comprise a power source. Power may be transferredwirelessly from the external unit to the internal unit. The wirelessenergy transfer may occur via electromagnetic induction. The powersource may comprise a pair of conducting members adapted to beinductively coupled. The internal unit may comprise one of theconducting members and the external unit may comprise the other.

The internal unit may comprise a data transfer mechanism for wirelesstransfer of data to the external unit. In a particular form, the datamay be transferred via the electromagnetic coupling. In another form, anRF transmitter/receiver may be used for wireless data transfer to theexternal unit.

The system may comprise alignment means for aligning the external unitwith the internal unit or intravascular device. The alignment means maycomprise a magnetic element. There may be a pair of magnetic elementscooperatively disposed on the external unit and the internal unit orintravascular device.

Additionally or alternatively, the power source may comprise at leastone of a battery or capacitor and RF transmitter/receiver.

The unit may comprise a microchip. The microchip may comprise amicroprocessor with signal amplifier and multiplexor.

The system may comprise a wireless transmission system for wirelesslytransmitting at least one of data and energy to or from theintravascular device.

The wireless transmission system may comprise at least one of a magneticinduction coil and an RF transmitter/receiver.

The system may comprise an alert system. The alert system may be adaptedfor signaling an alert when the sensed activity of neural tissue fallsoutside of a predetermined parameter.

The alert may comprise a warning signal which is activated when sensedelectrical activity indicates possible imminent onset of seizure in theanimal.

The system may comprise a device located separately to the intravasculardevice, the device being adapted for at least one of storage,processing, and transmission of data or energy to or from theintravascular device. The device may be directly connected to theintravascular device by a solid transmitting medium such as a wire orfiber optic cable. Additionally or alternatively, the intravasculardevice and the device may be wirelessly linked.

The device may comprise a wireless transmission mechanism fortransmitting at least one of data and energy between the intravasculardevice and the device, or between two devices.

The device may comprise an internal device. The internal device maycomprise an internal unit. The internal unit may be adapted forintravascular deposition. In another form, the internal unit may beadapted for subcutaneous deposition.

The device may comprise an external device. The external device maycomprise an external unit adapted for placement on or outside the body.

The external device may comprise a computer.

The device may comprise a prosthetic limb.

There may be multiple devices of same or different forms.

The system may further comprise alignment means for aligning theintravascular device, or internal device, with an external device. Thealignment means may comprise a pair of magnetic members cooperativelydisposed on the intravascular device, or internal device, and theexternal device.

The system may comprise multiple intravascular devices retained atvarious regions in one or more animal vessels. Thus, electrical activityof various regions of neural tissue proximate the intravascular devicesmay be sensed or stimulated.

In another aspect the invention may provide an apparatus for sensing orstimulating activity of neural tissue comprising:

an intravascular device for placement within an animal vessel, theintravascular device being adapted to sense or stimulate activity ofneural tissue located outside the vessel proximate the intravasculardevice, and

a retaining member for retaining the intravascular device at a regionwithin the vessel.

The animal vessel may comprise an artery, vein, or lymph vessel.

The animal vessel may comprise a mammalian vessel. In a particularaspect, the mammalian vessel may comprise a human vessel.

The human vessel may comprise a cerebral vessel. For instance, the humanvessel may comprise the anterior, middle, or posterior cerebral artery.

In a particular form, the human vessel may comprise the second or thirdbranches of the middle cerebral artery which track along the postcentral gyms of the brain.

In another aspect, the mammalian vessel may comprise a sheep vessel. Thesheep vessel may comprise the superior sagittal sinus.

The vessel may be between 1 and 5 millimeters in diameter at the regionwhere the intravascular device is to be retained. In a particular form,the vessel may be about 3 millimeters in diameter at the region wherethe intravascular device is to be retained.

The neural tissue may comprise brain tissue.

The brain tissue may comprise the post central gyrus. The brain tissue,or post central gyms, may comprise the motor homunculus.

The brain tissue may comprise the pre central gyms. The brain tissue, orpre central gyms, may comprise the sensory homunculus.

Thus, depending on the position of the intravascular device or devices,various regions of the brain may be sensed or stimulated, including thepre central gyrus and the post central gyms. This means that imaginedmovements of limbs or other parts of the body may be sensed when sensingactivity of the pre central gyms, or movements of the limbs or otherparts of the body may be activated when stimulating the post centralgyms.

Intravascular sensing of the electrical activity of various regions ofthe brain may be used for monitoring epileptic patients and detectingseizure focus points.

Intravascular stimulation of brain tissue may allow for preoperativebrain mapping.

Intravascular deep brain stimulation may be used in the treatment ofmedical conditions. The medical conditions may include Parkinson'sDisease, Depression, Obsessive Compulsive Disorder or Tourette'ssyndrome. Suitably, intravascular stimulation of deep brain tissue maybe used in the treatment of conditions including Parkinson's disease,depression or Obsessive Compulsive Disorder.

The system may comprise a brain computer interface (BCI).

In another aspect the invention may provide a method for sensing orstimulating electrical activity of neural tissue from within an animalvessel.

The method may comprise using an intravascular device to sense orstimulate the electrical activity of the neural tissue from within ananimal vessel proximate the neural tissue.

The electrical activity may comprise a local field potential.

The electrical activity may comprise an action potential. The electricalactivity may comprise activity of a single neuron.

The method may comprise guiding the intravascular device to a regionwithin the vessel proximate the neural tissue to be sensed orstimulated. The intravascular device may be guided through a catheter.

The method may comprise visualizing the vessel by a medical imagingtechnique in order to facilitate guidance of the intravascular device tothe region of the vessel. The medical imaging technique may compriseangiography.

The method may comprise retaining the intravascular device at the regionof the vessel. The intravascular device may be retained against theinner wall of the vessel. The method may comprise expanding a stent toretain the intravascular device against the vessel wall. The method maycomprise gradual biological decomposition of the stent.

The method may comprise gradual biological incorporation of theintravascular device into the vessel wall. The intravascular device, orretaining member, is still considered to be ‘in’ the vessel whenincorporated into the vessel wall or projecting into the vessel wallfrom within the vessel.

The method may comprise endothelialisation of the intravascular deviceinto the vessel wall. The method may comprise scarring of theintravascular device into the vessel wall.

The method may comprise amplifying a signal sensed by the intravasculardevice.

The method may comprise converting the signal from analogue to digital.

The method may comprise monitoring the signal. The signal may bemonitored external to the animal. The signal monitored may comprise anintravascular electroencephalographic (EEG) signal.

The method may comprise powering the intravascular device wirelessly.The intravascular device may be powered by passive induction.

The intravascular device may be powered by radio waves. The method maycomprise using radiofrequency identification to transfer data.

The method may comprise long term deposition of the intravascular devicein the animal vessel. The intravascular device may be deposited in theanimal vessel for multiple years. It may be deposited in the animalvessel for the remainder of the animal's lifetime.

The method may comprise sensing or stimulating electrical activity ofneural tissue from various regions in one or more animal vessels. Thus,the electrical activity of various regions of neural tissue may besensed or stimulated.

The neural tissue may comprise a deep brain region. Thus, the method maycomprise sensing or stimulating electrical activity of a deep brainregion from within an animal vessel.

The method may comprise retaining or depositing the intravascular devicewithin an animal vessel proximate a deep brain region.

The method may comprise detecting epileptic seizures, or the focusthereof, by monitoring intravascular EEG activity.

The method may comprise mapping quantities or properties of sensed orstimulated neural tissue. A property may comprise function. Thus, themethod may comprise mapping the function of sensed or stimulated neuralactivity. The method may comprise brain mapping. The method may comprisestimulating deep brain tissue in order to map its function.

The method may comprise stimulating deep brain tissue for treatment of amedical disorder. The disorder may comprise Parkinson's disease,depression, or obsessive compulsive disorder.

The method may comprise sending signals from the neural tissue to acomputer. The computer may receive signals relating to the electricalactivity of the neural tissue.

The method may comprise sending signals from a computer to the neuraltissue. These signals may be sent in response to the signals received.The neural tissue may receive command signals from the computer whichexcite the neural tissue.

The computer may be comprised of or by an external device.

The method may comprise sending signals from the neural tissue to anexternal device. These signals may be sent in response to signalsreceived by the neural tissue. The neural tissue may receive commandsignals from the external device which excite the neural tissue.

The external device may comprise an input device such as a keyboard ormouse. Thus an input device may be controlled by the animal.

The external device may comprise a prosthetic limb. Movement of theprosthetic limb may occur in response to neural tissue activity.Activation of neural tissue may occur in response to stimulation, suchas movement or touch, of the prosthetic limb.

The method may comprise wirelessly transmitting data or energy betweenthe intravascular device and a separate device adapted for storing,processing, or transmitting signals to or from the device.

The method may comprise retaining or depositing the intravascular devicewithin an animal vessel proximate a deep brain region. Electricalactivity of the deep brain region may be sensed or stimulated.

The method may comprise retaining or depositing the intravascular devicein a vessel traversing the hippocampus. This may allow detection ofseizures or imminent seizure threat.

The method may comprise sensing changes in electrical activity in thepre central gyms resulting from attempted movement of natural, absent,or artificial body parts.

The method may comprise causing movement of a natural or artificial bodypart by intravascularly stimulating the pre central gyms.

The method may comprise placing an external unit over a region of thebody proximate the intravascular device, or over a region of the bodyproximate an internal device linked to the intravascular device, inorder to facilitate wireless transmission between the external deviceand the intravascular device, or between the external device and theinternal device.

In another aspect, the invention may provide use of an intravasculardevice to sense or stimulate electrical activity of neural tissue fromwithin an animal vessel proximate the neural tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative but non-limiting embodiments of the invention will now bedescribed with reference to the drawings wherein:

FIG. 1 is a diagram showing a section of the second branch of the middlecerebral artery of a human prior to deposition of a wireless version ofan intravascular device with stent.

FIG. 2 is a diagram of the section of the middle cerebral artery shownin FIG. 1, with the stent expanded and the intravascular device retainedagainst the arterial wall.

FIG. 3 is a diagram showing the same region of the middle cerebralartery as FIG. 1 with the stent and the intravascular device depositedin the middle cerebral artery, and objects required for insertion anddeployment removed; the magnified portion shows the intravascular deviceand expanded stent.

FIG. 4 is a diagram with a magnified portion showing the intravasculardevice fused with the arterial wall, and the stent absent due tobiological decomposition.

FIG. 5 is a diagram showing how the intravascular device acts as a braincomputer interface with a prosthetic limb of a human being.

FIG. 6 is a diagram showing a section of the second branch of the middlecerebral artery of a human prior to deposition of a wired version of anintravascular device with stent.

FIG. 7 is a diagram of the section of the middle cerebral artery shownin FIG. 6, with the stent expanded and the intravascular device retainedagainst the arterial wall.

FIG. 8 is a diagram showing the same region of the middle cerebralartery as FIG. 6 with the stent and the intravascular device depositedin the middle cerebral artery and objects required for insertion anddeployment removed; the magnified portion shows the intravasculardevice, expanded stent, and wire bundle which connects externally.

FIG. 9 is a diagram showing the arterial pathway for insertion of anintravascular device adjacent brain tissue; a wired version of thedevice is shown.

FIG. 10 is a diagram showing a wireless version of the intravasculardevice deposited in the brain, with the intravascular devicetransmitting to and receiving signals from an external computing andmonitoring device.

FIG. 11 is a block diagram of the front end electronics of a wirelessversion of the intravascular device which is to be located within ananimal vessel.

FIG. 12 is a block diagram of the back end electronics of a wirelessversion of the intravascular device to be located external to the bodyof the animal.

FIG. 13 is a diagram of a further wired version of an intravasculardevice having an elongate probe with guide wire passing therethrough.

FIG. 14 is a diagram showing a subcutaneous pectorally located internaldevice which is wired back to the intravascular device in a brain vesseland inductively coupled to an external unit controlling a prostheticlimb.

FIG. 15 is a diagram of an internal unit.

FIG. 16 is a diagram of an external unit.

FIG. 17 is a block diagram illustrating possible electrical and dataflow within and between internal and external units.

FIG. 18 is a diagram illustrating various arrangements of internal andexternal units.

FIG. 19 diagrammatically illustrates a wireless version of theintravascular device which communicates directly with an external unitoverlying an adjacent region of the skull.

FIG. 20 is a diagram illustrating how the intravascular device may bedeposited in the hippocampal region of the brain for pre-seizuredetection or deep brain stimulation.

FIG. 21 is a diagram illustrating a testing procedure utilizingstimulating electrodes for mapping and identifying optimal regions forplacement of the intravascular device within a vessel.

FIG. 22 illustrates arterial vasculature traversing a human brain andpotential deposition sites for an intravascular device.

FIG. 23 illustrates venous vasculature traversing a human brain andpotential deposition sites for an intravascular device.

MODES FOR CARRYING OUT THE INVENTION

Referring to the drawings, there is shown a system, generally designated2, for sensing or stimulating activity of neural tissue 54, such asbrain tissue 192. The system 2 comprises an intravascular device 4 forplacement in an animal vessel 6, such as the second branch 166 (see FIG.22) of the middle cerebral artery 160 of a human being 8. A wirelessversion of the intravascular device 4 is shown in FIGS. 1-5 & 10, and awired version of the intravascular device 4 is shown in FIGS. 6 to 9.

The system 2 further comprises a retainer 12 for retaining theintravascular device at a region within the artery 6, and a flexiblemicro-catheter 10 which is to be passed up through the subject'svascular system and allows passage of the intravascular device 4therethrough.

As shows more clearly in FIG. 3, the wireless version of theintravascular device 4 comprises a 2 times 4 array of circularelectrodes 14.

The electrodes 14 are mounted on and project from the outer surface of arectangular semiconductor board 16 which in this instance is in the formof a soft printed circuit board in a silicone encasement.

Located centrally on an outer surface of the board 16, between two 2times 2 arrays of electrodes 14, is a rectangular shaped microchip 18.The microchip 18 is electrically connected to each of the electrodes 14by electrode wires 56.

In the wired embodiment shown in FIGS. 6 to 9, the microchip is omittedand the electrode wires 56 congregate to form a wire bundle 58 whichextends back through the vascular system and connects with an externalcomputing device 52 (see FIG. 9). Thus, in the particular wired versionof the intravascular device 4 shown, the external computing device 52performs the processing functions that the microchip 18 carries out inthe wired version.

The retainer 12 comprises a stent 20 and a flexible micro-tube probe 22which, in FIGS. 1 & 2, is attached to the stent at one end, and in FIGS.6 & 7, acts as a housing for the stent when the stent is in a contractedand retracted state.

The stent 20 has a mesh configuration or lattice framework, and is madeof a bio absorbable substance which breaks down gradually in the body,such as over a period of one to two years when deposited into a humanvessel. In an alternative embodiment the mesh stent is made of an inertmetallic substance which can remain functional in the body for severalyears or the life of the person.

The stent 20 as shown in FIGS. 6 to 8 is biased to expand. Thus, whenthe stent 20 is retracted in the micro-tube 22 it conforms to the innerwall of the micro-tube 22, and when it is ejected from the proximal endof the micro-tube it expands, conforming to the shape of the innerarterial wall (assuming the diameter of the inner wall of the vessel isless than that of the stent). The stent takes on a tubular shape whenallowed to fully expand.

The semi-conductor board 16 is mounted on the outer mesh surface of thestent 20 so that when the stent is expanded to take the shape of thevessel, the electrodes 14 of the intravascular device 4 are brought intocontact with the inner wall of the artery 6.

The guide catheter 10 has an internal diameter of about 0.15 mm which isenough to enable the passage of the micro-tube 22 with retracted stentand intravascular device therethrough.

FIG. 13 shows a wired version of the system 2 wherein the intravasculardevice 4 comprises a 2 times 4 array of electrodes 14 encased in asilicone flap 64.

The silicone flap 64 is mounted at the end of an elongate tubular shapedsilicone probe 22. Passing centrally through the probe is a guide wire62 and wire bundles 58. The wire bundles are formed from individualwires 56 which extend from respective electrodes which are attached tobut insulated from the guide wire 62.

The guide wire passes out of the patient's body to external processingequipment 34. As signal processing occurs externally, there is no needfor a microchip to be present in this version of the intravasculardevice.

A wired system 2 such as that shown in FIG. 13 may be used to sense orstimulate neural tissue in order to determine an appropriate locationfor deposition of a wireless version of the intravascular device.

The intravascular device 4 may be inserted and retained in the desiredregion of a vein or artery 6 by performing the following steps:

-   -   A radio opaque contrast agent is injected into the blood vessel        6 through which the catheter 10 is to be inserted. In this        instance, the contrast agent is injected into the femoral artery        or internal jugular vein in order to visualize blood vessels and        organs of the body using an imaging technique such as        radiography, CT and MR angiography.    -   The catheter 10 is then threaded into and through the femoral        artery, and further up through continuing branches of the        femoral artery until it reaches the desired position in the        second branch of the middle cerebral artery (see FIG. 9 for        vascular pathway of catheter). Alternatively, the catheter is        threaded into branches of the venous system, initially entering        the internal jugular vein up through the branches until entering        the superior sagittal sinus and desired position within the        cortical veins.    -   If not already present within the catheter 10, the micro-tube 22        with intravascular device 4 and stent 20 is threaded up through        the catheter 10 to proximate the region where the intravascular        device is to be retained (see FIG. 6).    -   The stent 20 is then protruded beyond the proximal end of the        micro-tube 22 which has housed it to this point. As the stent 20        is protruded beyond the end of the micro-tube 22 it expands to        take on the shape of the blood vessel wall 6, thereby retaining        the intravascular device 4 against the inner wall of the vessel        6.    -   In another form of the invention, the catheter 10 is omitted        from the system 2 and the micro-tube 22 acts as both the guide        for the stent through the vasculature, as well as the housing        for the stent before deposition.    -   Where long term deposition of the stent 20 is intended, the        micro-tube 22 may be detached and separated from the stent 20. A        voltage may be delivered to a discrete metallic area        interconnecting the micro-tube and the stent, thereby causing        induced thermal fatigue of the discrete area and detachment of        the stent.    -   If a new location of the intravascular device is desired, the        stent with intravascular device may be withdrawn back into the        micro-tube 22, and the system 2 moved to a desired region where        redeployment of the stent with intravascular device may then        take place.    -   For long term deposition of the intravascular device, the        catheter and detached micro-tube are withdrawn back through and        removed from the femoral artery, leaving the stent and        intravascular device retained at the desired arterial region.    -   In a wired version of the device, a device wire 58 formed from a        bundle of wires 56 extending from the electrodes 14 may remain        in the body during use of the intravascular device 4 (see FIGS.        8 & 9). In one form, the device wire 58 may extend from the        intravascular device all the way to and through the femoral        artery where it exits the body and attaches to external        monitoring or stimulating equipment (see FIG. 9) for short term        recording and monitoring during the angiography procedure.        Suitably, for longer term recording or monitoring, the device        wire may extend from the intravascular device, back through the        vasculature to a peripheral blood vessel such as the subclavian        artery when the intravascular device is retained in the arterial        system or the subclavian vein when the intravascular device is        retained in the venous system. At this point, the wire exits        through the vessel wall and into the subcutaneous tissue of the        pectoral region where it attaches to an internal unit 68 (see        FIG. 14).    -   In one form, the stent biologically decomposes gradually over        time, leaving only the intravascular device in place, and the        intravascular device is gradually endotheliolised into the inner        wall of the artery.    -   In another form, the stent is made of an inert material, such as        platinum or nitinol which is resistant to decomposition, thereby        leaving the stent to be incorporated along with the        intravascular device into the arterial wall by a process of        endothelialisation and/or scarring.

Depending on its location and function, neural tissue of the brainadjacent the intravascular device may be stimulated, or electricalactivity in this tissue may be changed, in various manners including:

-   -   By the patient actively moving a part of their body. For        example, a patient's active movement of their right arm may        result from electrical activity in the area of the motor        homunculus representing the arm in the pre central gyrus 90 of        the brain. In such instances, one or more intravascular devices        retained or deposited in a portion of the middle cerebral artery        or cortical veins adjacent to the motor homunculus may sense        electrical activity such as electroencephalography, local field        potentials or action potentials in this area of the brain.    -   By the patient attempting active movement of a part of their        body which is no longer present or to which neural connection        has been lost. For example, where a patient has had their right        arm amputated, attempts to move their absent right arm may still        produce a change in electrical activity in the arm portion of        the motor homunculus despite the arm not being present.    -   By part of the patient's body being passively moved by an        external force. For example, a physical therapist may passively        move a patient's right arm without any active muscle contraction        performed by the patient. Such passive movement may cause        increased activation of part of the sensory homunculus in the        post central gyms 190 relating to arm joint proprioception and        skin sensation, as well as sensory feedback resulting from the        pressure and warmth of the therapist's hands.    -   By pricking the patient's forearm with a pin 60, thereby causing        a change or increase in electrical activity in the sensory        portion of the brain associated with touch and pain in the hand        (see FIG. 10).    -   By the patient imagining, remembering or performing a new mental        activity, thereby causing electrical activity to be produced in        various regions of the brain.    -   By the patient developing an epileptic seizure. A foci of        electrical activity that sparks a seizure within brain tissue        may be detected with accurate spatial localisation by changes in        electroencephalography using one or more intravascular devices        near the area of seizure focus.    -   By involuntary intrinsic processes. For example, changes in        electrical activity in regions of the brain may result from        conditions or disease processes such as epilepsy, Parkinson's        disease, depression and Obsessive Compulsive Disorder. Deep        brain activity may be particularly affected by such conditions.

Once retained in the vessel, the intravascular device 4 may be used tosense the electrical activity, or changes in the electrical activity, ofadjacent extra vascular neural tissue, and the electrical activity maybe processed, in the following manner:

-   -   The electric charge emitted from the stimulated or pathological        adjacent neural tissue is sensed and collected by the electrodes        14, and conducted by wires 20 to the microchip 18 (see FIG. 3).        As shown in FIG. 11, the microchip houses a channel amplifier        24, filter 26, analogue to digital converter 28, and an RF        transmitter/receiver 30.    -   The signal from the electrodes 14 is passed to the channel        amplifier 24 which amplifies the signal from the electrodes.    -   The amplified signal is converted from analogue to digital by        the converter 28.    -   A microprocessor controlled induction coil or RF transmitter 30        then transmits the digital signal wirelessly to a corresponding        induction coil or RF receiver 32 which forms part of an external        processing system 34, such as a computer. The computer 34 also        comprises a power source 36, a signal display 38, signal        processor software 40 which is adapted to perform feature        extraction 42 and translation 44, and a brain computer interface        output 46 which in this instance is adapted to cause mechanical        limb movement 48 of a prosthetic limb 50. The signal display 38        is in the form of an intravascular EEG signal which is displayed        on a monitor 52.    -   The intravascular EEG signal may be processed by software which        enables feature extraction and translation for a brain computer        interface. The resultant BCI output 46 enables the patient to        control operation of devices in the external environment. This        may include movement of mechanical limbs 48 and control of        computer inputting devices such as mice or keyboards.    -   Monitoring the display signal may enable detection and diagnosis        of conditions in the brain, such as the detection of epileptic        seizures or parameters which indicate that a seizure is        imminent. Further, detection and monitoring of conditions such        as Parkinsons disease, depression, and Obsessive Compulsive        Disorder may be achieved by monitoring intravascular EEG signals        from adjacent deep brain regions.

Once retained or deposited in the artery 6, the intravascular device maybe used to stimulate regions of adjacent neural tissue in the followingmanner:

-   -   In the wireless version of the device 4, a signal is sent by the        external RFID receiver 32 and received by the RF        transmitter/receiver 30 of the intravascular device. The signal        may be sent in response to a signal transmitted by the        intravascular device 4 to the external computer 34, with the        response to the transmitted signal being determined by the        signal processor software 40.    -   The signal is then transmitted from the RF transmitter/receiver        30 to the electrodes in a form which may then be further        transmitted to the adjacent neural tissue, thereby causing        excitation or activation of a local field potential or action        potential in the adjacent neural tissue.

Intravascular neural stimulation may have various applications such asin preoperative mapping whereby areas of a patient's brain arestimulated to determine the nature of their function. The purpose ofpreoperative mapping may be to locate important or non-expendable areasof the brain that are not to be sacrificed during operations such asbrain tumour resections or epilepsy focus resections.

There may be many therapeutic applications for intravascular neuraltissue stimulation including deep brain stimulation in the treatment ofParkinson's disease, depression, Obsessive Compulsive Disorder andTourette's Syndrome. Advantageously such stimulation may be achievedwithout the need for invasive brain surgery.

It should be noted that several intravascular devices can be deployed inone or more vascular regions throughout the animal body in order tosense or stimulate neural tissue focused in one area or various areasthroughout the body. Sensing neural activity in various areas may beparticularly applicable when diagnosing and monitoring seizures inepilepsy.

Referring now to FIG. 14, there is shown a further system 2 comprisingan internal unit 68 located subcutaneously in the left pectoral region118 and connected by wire 58 back through the vasculature 6 to anintravascular device 4 deposited within a brain vessel 6. The systemfurther comprises an external unit 70 mounted externally on the skinoverlying the internal unit 68 and being inductively coupled therewith,the external unit being connected by wire 72 to a prosthetic limb 50.

As shown in FIG. 15, the internal unit 68 comprises an internal mountingmember 74 which defines suture holes 116 for fixing the unitsubcutaneously. Mounted on the internal mounting member 74 is aninternal microchip 76 comprising an application specific integratedcircuit. Also mounted on the internal mounting member is an internalmagnetic induction coil 78 connected to the internal microchip 76, aswell as an internal magnet 80.

The internal unit 68 in FIG. 15 is also shown having an internal RFtransmitter/receiver 82 and an internal battery or capacitor 84,although it is envisaged that the battery and RF transmitter/receivermay not be required in some versions of the internal unit, particularlywhere electrical and data transfer is already effectively achieved bywireless inductive coupling with the external unit. However, inclusionof a battery adapted to be charged by the inductive coupling may also beuseful as a back-up energy source when the external unit is moved tolocation remote from the internal unit and ceases to effectively produceenergy of its own.

The internal unit 68 further comprises an alert system in the form of aalert light 110 and a speaker 112, although it is envisaged that otheralert devices may be used, including vibrating devices.

FIG. 16 shows the external unit 70 which comprises an external magnet114, external microchip 86 with application specific integrated circuit,and an external magnetic induction coil 88 wired to the microchip, allmounted on an external mounting board. The external magnetic inductioncoil 88 and external magnet 80 are arranged to correspond with likecomponents of the internal unit 68.

The external unit 70 is located on the skin overlying the internal unit68. Attraction between the internal and external magnets of therespective units facilitates achievement of optimal alignment fortransmission between the internal and external magnetic induction coils.

The external unit 68 in FIG. 16 is also shown having an external RFtransmitter/receiver 122 and an external battery or capacitor 120,although it is envisaged that the battery and RF transmitter/receivermay not be required in some versions of the external unit, particularlywhere electrical and data transfer is already effectively achieved bywireless inductive coupling with the external unit.

The external unit 70 further comprises a connection port 124 enablingconnection of the external unit 70 with cable 126 which may in turn beconnected to an external device such as a computer or power outletthereby enabling wired transfer of data and energy between the externalunit 70 and another external device.

Also comprised by the internal unit 69 is an alert system in the form ofan alert light 110 and a speaker 112, although it is envisaged thatother alert devices may be used, including vibrating devices. The alertsystem may be used for various alerts including in cases of low power,device or system malfunction, completed periods of monitoring orrecording, or current or impending medical pathology or irregularity.

The incorporation of a power source and information processor in theinternal unit version shown in FIG. 15 means that these features maypotentially be omitted from the intravascular device of the system shownin FIG. 14. Thus, the deposited intravascular device in this system maybe similar to intravascular device previously discussed with respect toFIG. 8, i.e. not having its own power source or microchip, butcomprising electrodes 14 and a wire bundle 58 which extends down throughthe vasculature to connect with the microchip 76 of the internal unit.

In the system of FIG. 14, the intravascular device 4 is located in aportion of a vessel 6 adjacent the motor homunculus. In this instance,the intravascular device 4 was passed into the internal jugular vein 170and guided up through the sigmoid sinus 172, transverse sinus 174 andinto the superior sagittal sinus 178 where it is deposited. It isenvisaged, however, that other routes and places of deposition may alsobe suitable, including places for deposition such as the cerebral veins184 (see FIG. 23) branching off the superior sagittal sinus, other veinslying adjacent the motor cortex, the second branch of the middlecerebral artery 160 (see FIG. 22), and other arteries lying adjacent themotor cortex.

Attempted active movement of the prosthetic limb 50 by the human being 8results in generation of action potentials in the upper limb homuncularregion of the precentral gyrus. The resultant cortically originatingchanges in electrical potential are sensed by the electrodes 14 of theintravascular device 4 and transmitted along the wire bundle 58 to themicrochip 76 of the internal unit 68.

FIG. 17 illustrates possible flow of data and/or energy between theintravascular device 4, internal unit 68, external unit 70, and externaldevice which comprises a prosthetic limb 50 in this instance.

As previously mentioned, the electrical signal passes from theelectrodes 14 to the internal microchip. The internal microchip 76comprises an application specific integrated circuit with microprocessor92 for processing the received signal. The microchip further comprisesan amplifier 94 for amplifying the signal, and a multiplexer 96 fordigitally converting the signal, before the signal is passed to theinternal inductive loop 78 and wirelessly transmitted through thecutaneous pectoral tissue to the external coil 88 of the external unit70.

The external unit passes the signal through its own external microchip98 with microprocessor 100 which decodes the signal. The externalmicrochip further comprises a rectifier 102 for converting the signaland an amplifier 104 for amplifying the signal. The signal is decoded bythe microprocessor and the decoded signal is used to controlmicroprocessors and motors on the prosthetic limb 50, thereby causingmovement of the limb to occur in accordance with the area and degree ofprecentral gyms activation.

The prosthetic limb comprises sensors 114 (see FIG. 14) adapted to sensetouch, temperature, pressure or vibration in the area of the sensor 114.The sensors are smaller and more tightly packed anteriorly in therobotic fingers than in the robotic forearm, thereby providing morefinely tuned sensation in the fingers for grasping and handling objects.

When activated, the sensors 114 send electrical signal from theprosthetic limb to the external unit where the signal is processed andconducted across the skin to the internal unit where further processingoccurs, before the signal is passed up to the intravascular device 4, oranother intravascular device 4, deposited adjacent the post-centralgyrus. Here, the electrodes stimulate the area of brain corresponding tothe signal received from the sensors 144, such that the patient is ableto feel what is sensed by the prosthetic limb.

Additionally or alternatively, the signal from the sensors 114 may bepassed up to another intravascular device located in a vessel adjacentthe precentral gyrus. This signal causes the intravascular electrodes 14to stimulate the adjacent neural tissue of the motor homunculus, therebycausing movement of the limb such as may reflexively occur when themuscle spindles of a natural limb are quickly stretched or the skin isburnt.

FIG. 18 illustrates various methods of connection from the intravasculardevice 4 to the prosthetic limb 50 via internal and external units, 68and 70 respectively. As was evident in the system of FIG. 14, method “C”shows a wire 58 running from an intravascular device (not shown) throughthe vessel 6 before piercing the vessel wall and connecting with anextravascular subcutaneous internal unit 68. The internal unitcommunicates wirelessly with an adjacent external unit 70 mounted on theskin 128, which external unit is wired to the prosthetic limb 50. It isenvisaged that regions other than the pectoral region may also besuitable for placement of the internal and external units, such as theneck region.

Method “A” shows an intravascularly placed internal unit 68 c, which iswired to an intravascular device 4 (not shown) communicating wirelesslywith an external unit 70 disposed on the skin 128 and wired to theprosthetic limb 50. Rather than having a processor and wirelesstransmission system located on the intravascular device, thisarrangement allows the processor and/or wireless transmission system tobe located on the internal unit, meaning that the intravascular devicemay be of smaller size, and the wireless transmission system may beplaced in a region which is more suitable for wireless transmission toan external unit.

Method “B” shows a double induction coupling system whereby anintravascular internal unit 68 a, which is wired to an intravasculardevice (not shown) communicates wirelessly across the vessel wall withan adjacent proximal extravascular internal unit 68 b. The internal unit68 b is in turn wired to a distal subcutaneous internal unit 68 c thatcommunicates wirelessly across the skin 128 with an external unit 70which is mounted externally on the skin and wired to the prostheticlimb. This arrangement potentially allows for more closely coupledwireless transmissions and avoids piercing of tissues such as vesselsand skin.

Method “D” provides for an intravascular device 4 (not shown) which iswired directly to an external unit 70 located on the surface of theskin, which external unit is connected by wire 72 to the prostheticlimb. Thus, no internal unit is present in this arrangement.

Referring now to FIG. 19 there is shown a system 2 comprising a wirelessversion of an intravascular device 4 which is inductively coupled to anexternal unit placed over the skin adjacent the region of deposition ofthe intravascular device. As shown in the inset, intravascular device 4comprises an array of electrodes 14 connected by wires 56 to a microchip18 which is in turn connected to an internal magnetic induction coil 78.The intravascular device further comprises an internal magnet 80 forfacilitating optimal placement of the external unit by magneticattraction. The external unit 70 shares the same features as that shownin FIG. 16, and is connected by wire 72 to the prosthetic limb 50.

The system 2 of FIG. 19 works in a similar fashion as that shown in FIG.14 except rather than the electrical signal received by the electrodesbeing passed by wire 58 down through the vasculature to an internalunit, the signal passes directly from electrode wires 56 into themicrochip 18 where similar processing as occurred in the internal unittakes place. The processed signal is then transmitted via magneticinduction to the external unit 70 mounted on the adjacent portion ofskin overlying the skull.

FIG. 20 shows yet another system 2 wherein the intravascular device isspecifically lodged in a vessel 54 traversing the hippocampus 54. Forinstance, intravascular device 4 may be entered into the vascular system6 via the cavernous sinus and passed up therethrough before beingdeposited in the internal cerebral vein or one of its branches 186 (seeFIG. 23). Here, intravascular device can be used as an early warningseizure detection system, whereby abnormal excitation in hippocampaltissue adjacent the intravascular device is sensed by the electrodes ofthe device, and the electrical signal is in turn transmitted to aninternal unit 68 which is located subcutaneously in the pectoral regionin this instance, although it is envisaged that the wire could rundirectly to an external unit 70 mounted on to the outer surface of theskin. Here, an alert system in the form of an alert light 110 or speaker112 may be activated to cause the emission of light or sound, therebyalerting the user that a seizure may be imminent, and allowing them totake necessary prophylactic action such as the ingestion ofanti-epileptic drugs.

The internal unit may draw energy from an internal battery or capacitor84 which is adapted to be charged by magnetic induction when theexternal units is located adjacent the internal unit. Thus, thisarrangement allows the external unit to be situated remotely from theuser, only being fastened to the skin overlying the internal unit whentransfer of data or charging of the battery or capacitor is required.Alternatively, there may be no external unit, and the internal unit mayoperate on a long life battery, such as those used in cardiacpacemakers, activating alert signals when the hippocampal signalthreshold is passed.

The embodiment of FIG. 20 also shows an external unit connected to a box132 which is adapted to measure and compute signals received. In anotheraspect, the box 132 may be adapted to send electrical signals to theexternal unit, where the signals are conducted to the internal unit andpassed up by wire to the intravascular device, thereby activating theelectrodes to stimulate adjacent deep cortical tissue. Thus, brainstimulation may be achieved in such a fashion, with placement of theintravascular device varying depending on the region of the brain to bestimulated.

FIG. 21 illustrates how testing may be conducted to map or identifyoptimal placement of the intravascular device 4. For example, testingmay occur preoperatively in humans prior to long-term deposition of anintravascular device, or may be performed in animals for mapping optimallocations in like structures to humans.

In the testing procedure, the intravascular device 4 is retained in alocation within a vessel for testing. A hole is drilled through the skinlayer, skull and dura, and stimulating electrodes 134 are inserted intothe subarachnoid space 136 and subdural space 138 beneath the skull 140,sub-dermally, and externally on the skin, with each of the devices beingconnected by wires 142 back to an external stimulating box 132. Undercontrol of the box 132, the electrodes 134 are used to stimulate areasof the brain which are desired to be sensed, and the signal detected bythe intravascular device 4 is recorded. The procedure is then repeatedwith the intravascular device retained in different regions in thevessel to determine where optimal signal sensing occurs. This locationmay be suitable for long term deposition of an intravascular device forsensing and/or stimulating purposes.

FIG. 22 illustrates arterial vasculature which leads to and traverses ahuman brain, providing potential pathways for passage, and sites fordeposition, of one or more intravascular devices. Specificallyreferenced is the common carotid artery 150, external carotid artery152, internal carotid artery 154, ophthalmic artery 156, anteriorcerebral artery 158, middle cerebral artery 160, anterior choroidalartery 162, posterior communicating artery 164 and the second branch ofthe middle cerebral artery 166 in which an intravascular device 4 isdeposited.

FIG. 23 illustrates venous vasculature which leads traverses and passesfrom a human brain, providing potential pathways for passage, and sitesfor deposition, of one or more intravascular devices. Specificallyreferenced is the internal jugular vein 170, sigmoid sinus 172,transverse sinus 174, straight sinus 176, superior sagittal sinus 178,falx cerebri 180, inferior sagittal sinus 182, cortical veins 184, inone of which an intravascular device 4 is deposited, and internalcerebral vein 186 and its deep branches, in one of which anintravascular device 4 is deposited.

Where the terms “comprise”, “comprises”, “comprised” or “comprising” areused in this specification, they are to be interpreted as specifying thepresence of the stated features, integers, steps or components referredto, but not to preclude the presence or addition of one or more otherfeatures, integers, steps, components to be grouped therewith.

1. (canceled)
 2. A method for enabling a patient to control an externaldevice by performing a mental activity, the method comprising:implanting a stent structure within a cerebral vessel adjacent to abrain tissue, the stent structure having a plurality of discreteelectrodes each having an electrode surface, wherein the plurality ofdiscrete electrodes are configured to sense an electrical activity ofthe brain tissue located outside the cerebral vessel; expanding thestent structure to take a shape of the cerebral vessel such thatexpansion of the stent structure brings the electrode surface of each ofthe plurality of electrodes into contact with a wall of the cerebralvessel without expanding or altering a shape of the electrode surface ofeach of the plurality of discrete electrodes, wherein the wall of thecerebral vessel is adjacent to the brain tissue stimulated by thepatient; sensing electrical activity of the brain tissue using at leastone of the plurality of electrodes after the patient performs the mentalactivity; transmitting the electrical activity to an internal unit whichgenerates a signal that controls the external device, wherein theelectrical activity from the plurality of electrodes conducts wirelesslyto the internal unit, wherein the internal unit is located exterior tothe cerebral vessel; and where the internal unit is further configuredto transmit the signal to the external device such that the patientcontrols operation of the external device by stimulating a region of thebrain.
 3. The method of claim 2, wherein the plurality of discreteelectrodes is arranged in an array.
 4. The method of claim 2, whereinthe stent structure comprises a mesh stent.
 5. The method of claim 2,wherein the stent structure comprises a biodegradable or bioabsorbablesubstance.
 6. The method of claim 2, wherein transmitting the signalfrom the internal unit to the external device comprises inductivelycoupling the internal unit to an external unit, where the external unitis mounted externally to the patient.
 7. The method of claim 6, furthercomprising a data transfer mechanism configured for wireless transfer ofdata from the internal unit to the external unit.
 8. The method of claim7, wherein the internal unit comprises a RF transmitter.
 9. The methodof claim 7, wherein the external unit comprises a RF transmitter. 10.The method of claim 2, further comprising positioning a plurality ofadditional stent structures each having an array of electrodes withinvarious regions of one or more cerebral vessels for sensing electricalactivity of multiple additional regions of brain tissue.
 11. The methodof claim 2, wherein the external device comprises a prosthetic limb,wherein transmitting the signal from the internal unit causes movementof the prosthetic limb.
 12. The method of claim 2, wherein the stentstructure is positioned in a second branch or a third branch of a middlecerebral artery which tracks in or along a post-central gyms of thebrain.
 13. The method of claim 2, further comprising sensing changes inthe electrical activity in a pre-central gyrus of the brain tissueresulting from attempted movement of natural, absent, or artificial bodyparts coupled to the patient.
 14. The method of claim 2, furthercomprising transmitting a second signal from the external device to theinternal unit, wherein the second signal is electrically conducted tothe plurality of discrete electrodes to produce a stimulated electricalactivity of the brain tissue.
 15. The method of claim 14, furthercomprising transmitting the second signal to the stent structure. 16.The method of claim 2, further comprising a probe coupled to the stentstructure.
 17. The method of claim 16, wherein the probe comprises anelongate flexible micro-tube.
 18. The method of claim 2, furthercomprising a system electrically coupled to the plurality of electrodesand delivering an alert using the system when the electrical activity ofthe brain tissue falls outside of a predetermined parameter.
 19. Themethod of claim 2, further comprising passing a guide member into andthrough the cerebral vessel, the guide member being adapted for guidingthe stent structure to a region within the cerebral vessel proximate thebrain tissue to be sensed.
 20. The method of claim 2, further comprisingstimulating electrical activity of the brain tissue from within thecerebral vessel proximate the brain tissue using the plurality ofelectrodes.